It is well known in the oil and gas industry that moving casing during cementing operations provides improved cement jobs to isolate different producing formations, aquifers, etc. Generally, there are two ways to move the casing during cementing, reciprocation and rotation. Both reciprocation and rotation of casing rely upon use of the rig at the surface to rotate or reciprocate the entire casing string, which may be undesirable for operational or safety considerations. The bottom section of casing is the most critical portion, requiring a quality cement job and resultant seal in the annulus between the casing and the borehole. Achieving an improved cement seal in the annulus at the surface casing bottom helps assure a seal and prevents any fluid migration resulting in potential contamination of surface aquifers. Also, improving the seal around the bottom of intermediate casing strings enhances the ability of the cement to prevent annular flow during well control events and prevents communication from multiple producing zones. Finally, improving the seal across the bottom section of the production casing improves the isolation of the productive interval and prevents undesirable water production which can impede and limit hydrocarbon production.
Furthermore, there is a significant need in the oil and gas industry to provide an extended length rotating tool or tubing section at a predetermined location during a workover operation or to drill out a bridge plug. This would allow rotation at the distal end of coiled tubing or a work string by utilizing hydraulic energy and eliminate the need for rotation at the surface. Although it is currently known to use downhole hydraulic motors, these motors have a very limited length and application since only a small portion on the distal end actually rotates.
This disclosure solves these needs, by providing a method and apparatus for rotating a subsurface drill string such as a casing section without rotation at the surface.